Catalyst for producing unsaturated nitrile

ABSTRACT

A catalyst composition represented by the following empirical formula which is useful in production of unsaturated nitrites by ammoxidation: 
     
       
         Mo 10 Bi a Fe b Sb c Ni d Cr e F f G g H h K k X x Y y O i (SiO 2 ) j   
       
     
     wherein F represents at least one element selected from the group consisting of zirconium, lanthanum and cerium, G represents at least one element selected from the group consisting of magnesium, cobalt, manganese and zinc, H represents at least one element selected from the group consisting of vanadium, niobium, tantalum and tungsten, x represents at least one element selected from the group consisting of phosphorus, boron, and tellurium, Y represents at least one element selected from the group consisting of lithium, sodium, rubidium and cesium, the suffixes a-k, x and y represent a ratio of atoms or atomic groups, and a=0.1-3, b=0.3-15, c=0-20, d=3-8, e=0.2-2, f=0.05-1, e/f&gt;1, g=0-5, h=0-3, k=0.1-1, x=0-3, y=0-1, i is the number of oxygen produced by bonding of the above respective components, and j=0-100.

This application is the national phase of international applicationPCT/JP99/02146 filed Apr. 22, 1999 which designated the U.S.

TECHNICAL FIELD

The present invention relates to a metal oxide catalyst used inproduction of unsaturated nitriles by ammoxidation.

PRIOR ART

Hitherto, various compositions of catalysts have been disclosed ascatalysts suitable for production of unsaturated nitriles byammoxidation, for example, production of acrylonitrile by ammoxidationof propylene, production of methacrylonitrile by ammoxidation ofisobutylene or tertiary buthanol, etc. For example, U.S. Pat. No.3,226,422 discloses oxide catalysts containing molybdenum, bismuth andiron, and JP-B-38-19111 discloses oxide catalysts containing iron andantimony. Thereafter, improvement of the catalysts have been intensivelyattempted, and, for example, U.S. Pat. No. 4,290,922 discloses oxidecatalysts containing molybdenum, cobalt, nickel, bismuth, vanadium,calcium and potassium as essential components and zirconium and/orchromium as optional components, Japanese Pat. No. 2640356 disclosesoxide catalysts containing molybdenum, bismuth, iron, nickel and analkali metal element, U.S. Pat. Nos. 5,093,299 and 5,175,334 discloseoxide catalysts containing molybdenum, bismuth, iron, nickel, magnesium,potassium and cesium, JP-A-7-47272 discloses oxide catalysts containingat least one element selected from the group consisting of molybdenum,bismuth, iron, nickel, chromium and indium and an alkali metal elementsuch as potassium as essential components and at least one elementselected from the group consisting of manganese, magnesium, zinc,cerium, sodium and phosphorus as optional components, JP-A-7-328441discloses oxide catalysts containing molybdenum, bismuth, cerium, iron,nickel and magnesium or zinc, and an alkali metal, U.S. Pat. No.5,132,269 discloses oxide catalysts containing iron, antimony,molybdenum and bismuth or tellurium, and potassium.

These catalysts of the prior art have some effects for improvement inthe yield of unsaturated nitrites, but the improvement is stillinsufficient. In this technical field, it has been desired that yield ofunsaturated nitrites is further increased and, besides, combustion ofammonia which often occurs in the case of using catalysts higher inmolybdenum content is inhibited to reduce production of by-products suchas nitrogen oxide which causes problems in the protection ofenvironment.

DISCLOSURE OF THE INVENTION

As a result of intensive research conducted by the inventors in anattempt to solve the above problems in the prior art, it has been foundthat in the catalysts containing molybdenum, bismuth, iron, antimony,etc., coexistence of chromium and at least one element selected from thegroup consisting of zirconium, lanthanum and cerium results in highyields of unsaturated nitrites which cannot be attained with addition ofthe elements each alone.

These additive elements give synergistically favorable effects. Titaniumand hafnium which belong to the same group as zirconium did not showsuch effects. Rare earth metal elements of the lanthanum group otherthan lanthanum and cerium also did not show such special effects.

Chromium and at least one element selected from the group consisting ofzirconium, lanthanum and cerium show clear effects with addition of themin relatively small amounts, and addition in excess amount rather causessharp reduction of the yield of the desired products. Furthermore, inthe addition of them, the lower proportion of zirconium, lanthanum andcerium to chromium is preferred, and increase of the proportion resultsin increase of ammonia combustion and reduction of the yield of thedesired products. By using in combination chromium and at least oneelement selected from the group consisting of zirconium, lanthanum andcerium and by finding the preferred relation in the amounts of them inaddition, yield of the desired products can be improved and, besides,combustion of ammonia can be inhibited and yield of by-products can bereduced.

That is, the present invention provides a catalyst compositionrepresented by the following empirical formula which is used inproduction of unsaturated nitriles by ammoxidation.

Mo₁₀Bi_(a)Fe_(b)Sb_(c)Ni_(d)Cr_(e)F_(f)G_(g)H_(h)K_(k)X_(x)Y_(y)O_(i)(SiO₂)_(j)

In the above formula, Mo, Bi, Fe, Sb, Ni, Cr and K represent molybdenum,bismuth, iron, antimony, nickel, chromium and potassium, respectively, Frepresents at least one element selected from the group consisting ofzirconium, lanthanum and cerium, G represents at least one elementselected from the group consisting of magnesium, cobalt, manganese andzinc, H represents at least one element selected from the groupconsisting of vanadium, niobium, tantalum and tungsten, X represents atleast one element selected from the group consisting of phosphorus,boron and tellurium, Y represents at least one element selected from thegroup consisting of lithium, sodium, rubidium and cesium, O representsoxygen and SiO₂ represents silica, the suffixes a, b, c, d, e, f, g, h,i, j, k, x and y represent a ratio of atoms or atomic groups, and in thecase of Mo=10, a=0.1, b=0.3-15, c=0-20, d=3-8, e=0.2-2, f=0.05-1, e/f>1,g=0-5, h=0-3, k=0.1-1, x=0-3, y=0-1, number of oxygen produced bybonding of the above respective components, and j=0-100.

On the other hand, efforts have been made for increasing yield of thedesired oxidation products by improving preparation method of catalysts.For example, U.S. Pat. No. 3,350,323 discloses a method of adding anaqueous bismuth citrate solution to an aqueous molybdic acid solution,JP-A-53-10387, JP-A-53-10388 and U.S. Pat. No. 3,847,831 disclosemethods of adding a bismuth compound in solid state to an aqueousmolybdic acid solution, U.S. Pat. No. 4,418,007 discloses a method ofsimultaneously adding an aqueous solution of a bismuth salt and aqueousammonia to an aqueous molybdic acid solution having a pH of 6-8, U.S.Pat. No. 4,388,226 discloses a method of adding an aqueous solution of abismuth salt to a suspension of a molybdenum compound, U.S. Pat. Nos.4,212,766, 4,148,757 and 4,040,978 disclose methods of previouslyforming various molybdates, JP-B-52-22359 and U.S. Pat. No. 3,872,148disclose methods of previously forming various bismuth compounds, U.S.Pat. No. 4,803,190 discloses a method of using bismuth oxide or bismuthoxycarbonate as a bismuth source, JP-A-2-59046 discloses a method ofadjusting pH of a slurry containing at least one element selected fromthe group consisting of iron, bismuth and tellurium and a molybdenumcompound to higher than 7, U.S. Pat. No. 5,059,573 discloses a method ofadding a chelating agent to a molybdenum compound-containing slurrycontaining silica to adjust pH to 6 or higher, and U.S. Pat. No.5,071,814 discloses a method of adjusting a slurry containing molybdenumto a pH of 6 or higher and then mixing a bismuth compound therewith.

As mentioned above, various methods have been proposed for attainingimprovement of catalyst performance, such as devising the method ofmixing aqueous molybdenum solution with bismuth compound or specialselection of starting materials for bismuth. However, when these methodsare applied to production of molybdenum-bismuth-containing compositeoxide catalysts containing at least one metallic element selected fromthe group consisting of divalent metallic elements and trivalentmetallic elements, yield of the desired oxidation products is notnecessarily satisfactory.

BEST MODE FOR CARRYING OUT THE INVENTION

Molybdenum, bismuth, iron, nickel, chromium, potassium and the metallicelement represented by F are essential components, and unless they arewithin the above compositional ranges, the object of the presentinvention cannot be attained.

When the catalyst composition of the present invention contains ironantimonate, it naturally contains antimony, and in this case, there areadvantages that, for example, especially, selectivity of the desiredproduct is improved and physical properties of the catalyst are alsoimproved.

Moreover, when the catalyst of the present invention is used as afluidized bed catalyst, silica is preferably used as a carrier and inthis case, j=20-80 is a preferred range.

The catalyst composition of the present invention can be prepared bysuitably selecting the preparation methods disclosed as conventionaltechniques.

Molybdenum oxide, ammonium paramolybdate, etc. are used as startingmaterials for the molybdenum component; bismuth trioxide, bismuthnitrate, bismuth carbonate, bismuth oxalate, etc. are used as startingmaterials for bismuth component; iron nitrate, iron oxalate, etc. areused as starting materials for the iron component; chromium nitrate,chromic acid, etc. are used as starting materials for the chromiumcomponent; and potassium hydroxide, potassium nitrate, etc. are used asstarting materials for the potassium component.

Moreover, zirconium oxide, zirconium oxynitrate, etc. are used asstarting materials for the zirconium component; lanthanum oxide,lanthanum nitrate, etc. are used as starting materials for the lanthanumcomponent; and cerium oxide, ammonium cerium nitrate, etc. are used asstarting materials for the cerium component. In addition, organic acidsalts of these elements can also be used.

As starting materials for components such as nickel, cobalt, magnesium,manganese and zinc, it is convenient to use nitrates thereof, butorganic acid salts, hydroxides and oxides thereof can also be used.

In the case of adding a tellurium component, telluric acid or saltsthereof or tellurous acid or salts thereof can be used as startingmaterials of the tellurium component, and, besides, a solution preparedby dissolving metallic tellurium in a heated aqueous hydrogen peroxidemay also be used.

As starting materials for other components, oxides, hydroxides,nitrates, organic acid salts, etc. of the elements are used.

As starting materials for silica, silica sols, fumed silica, etc. areused, and silica sols are especially preferred. As silica sols, it ispreferred to use those of low sodium content.

The catalyst composition of the present invention is prepared by mixingthese starting materials, drying the mixture, and calcining it, and itis preferred to adjust the slurry prepared by mixing the startingmaterials to have a pH of 6 or higher. By this operation, ammoniacombustibility at the time of reaction is reduced, and yield of thedesired product is improved. In this case, the operability can beimproved by adding a chelating agent to the slurry to lower viscosity ofthe slurry. When the catalyst composition of the present invention witha pH of 6 or higher is prepared, it has been found that presence ofchromium component contributes to lowering of viscosity of the slurry.This is advantageous for improving operability and is to be noticed.

Further heat treatment of the prepared slurry is sometimes usefulbecause stability of the slurry increases and reproducibility isimproved.

The chelating agents usable here include ethylenediaminetetraaceticacid, lactic acid, citric acid, tartaric acid and gluconic acid.

Amount of the chelating agents added is preferably 0.1-10% by weight,more preferably 0.5-8% by weight based on the weight of the oxidecatalyst produced. If the amount of the chelating agents is less than0.1% by weight based on the oxide catalyst, the effect is notsufficiently developed, and if it is more than 10% by weight, theresulting catalyst is sometimes cracked considerably. In preparation ofa solution containing iron ion and chelating agent, amount of thechelating agent is preferably 0.1-2 gram molecule per 1 gram ion ofiron.

In the case of containing iron antimonate, preferably the ironantimonate is previously prepared and then mixed with the startingmaterials for molybdenum and other components to form a slurry.

As further improved preparation methods, preferred is a method whichcomprises mixing an aqueous slurry having a pH of 6 or higher andcontaining at least a part of the starting material for molybdenum andthe starting material for at least one element selected from the groupconsisting of nickel, cobalt, magnesium, chromium, manganese and zincwith a solution or slurry containing the starting material for telluriumand/or the starting material for iron, and drying and calcining themixture. Especially, in the case of a catalyst containing both telluriumand iron, preferred is a method which comprises mixing a solution orslurry containing the starting material for iron, a solution containingthe starting material for tellurium and said aqueous slurry having a pHof 6 or higher or mixing a mixed solution or slurry containing thestarting material for iron and the starting material for tellurium withsaid aqueous slurry having a pH of 6 or higher, and then drying andcalcining the mixture.

Another preferred method comprises heat treating an aqueous slurryhaving a pH of 6 or higher and containing at least a part of thestarting material for molybdenum and the starting material for at leastone element selected from the group consisting of nickel, cobalt,magnesium, chromium, manganese and zinc at a temperature of 50-120° C.,preferably 60-120° C. for at least 10 minutes, thereafter mixing thestarting material for tellurium or the starting material for iron orboth the starting materials for tellurium and iron with said heattreated slurry, and then drying and calcining the mixture.

As the starting materials for iron, there may be used ferrous oxide,ferric oxide, tri-iron tetroxide, ferrous nitrate, ferric nitrate, ironsulfate, iron chloride, organic acid salts of iron, iron hydroxide, etc.Moreover, a solution obtained by dissolving metallic iron in heatednitric acid may also be used. The solution containing the iron componentmay be used with adjusting the pH with aqueous ammonia or the like. Inadjusting the pH, precipitation of the iron component can be preventedby allowing a chelating agent to coexist in the solution containing theiron component, and highly active catalysts can be obtained. Thechelating agents usable here include, for example,ethylenediaminetetraacetic acid, lactic acid, citric acid, tartaric acidand gluconic acid.

In the above methods, it is preferred to carry out drying of the slurrymixture by a spray drying method and carry out granulationsimultaneously with the drying in the case of producing fluidized bedcatalysts. In this way, fine spherical particles can be obtained.

After drying, said mixture is preferably calcined at 200-500° C. andfurther calcined at 500-700° C. The calcining time can be 1-20 hours.The atmosphere in calcining is preferably oxygen-containing gas. Thecalcining is conveniently carried out in the air, but can also becarried out in the atmosphere of suitable mixture with oxygen andnitrogen, carbon dioxide, water vapor, organic compounds, etc. Box-typekiln, tunnel kiln, rotary kiln, fluidization kiln, etc. can be used forthe calcining. In the case of the catalyst being a fluidization bedcatalyst, it is especially preferred to carry out the final calcinationby a fluidization kiln. Thus, severe control of the final calcinationconditions can be easily performed, and fluidized bed catalysts ofexcellent performances can be produced with satisfactoryreproducibility. The particle diameter of the thus produced fluidizedbed catalysts is preferably 10-200 μm.

The catalyst compositions of the present invention or the catalystcompositions produced by the method of the present invention aresuitable for production of unsaturated nitriles by ammoxidation ofolefins.

The ammoxidation reaction is usually carried out using a supply gashaving the composition in the range of starting organiccompound/ammonia/air=1/0.9-1.3/8-12 (molar ratio) at a reactiontemperature of 370-500° C. and a reaction pressure of normal pressuresto 500 kPa. The apparent contact time is 0.1-20 seconds.

The present invention will be explained in more detail by the followingexamples.

Activity Test of Catalysts

Ammoxidation of propylene was carried out as an example of ammoxidationreaction.

The catalyst was packed in a fluidized bed type reactor of 400 mm inheight and 25 mm in inner diameter of catalyst fluidization part, and amixed gas having the composition of propylene/ammonia/air/watervapor=1/1.2/10/0.5 (molar ratio) was supplied into the reactor at a gaslinear speed of 4.5 cm/sec. The reaction pressure was 200 kPa.

Contact time (sec)=volume (ml) of the catalyst based on apparent bulkdensity/flow rate (ml/sec) of the supplied gas calculated in terms ofreaction conditions.

Yield of acrylonitrile (%)=the number of mols of the producedacrylonitrile/the number of mols of the supplied propylene×100.

Selectivity of acrylonitrile (%)=the number of mols of the producedacrylonitrile/the number of mols of the consumed propylene×100.

Conversion of propylene (%)=the number of mols of the consumedpropylene/the number of mols of the supplied propylene×100.

Combustion rate of ammonia (%)=100 [(weight of nitrogen in theproduct+weight of nitrogen in the residual ammonia)/weight of nitrogenin the supplied ammonia×100]

EXAMPLE 1-1

A catalyst having the composition ofMo₁₀Bi_(0.3)Fe_(4.4)Sb_(4.2)Ni_(5.75)Cr_(0.5)Zr_(0.2)K_(0.7)P_(0.2)Te_(0.25)O_(53.7)(SiO₂)₄₀(atomic ratio) was prepared.

250.6 g of ammonium paramolybdate was dissolved in 1730 g of pure water,and, then, 3.3 g of 85% phosphoric acid was added to the solution. Theresulting solution was mixed with 1750 g of 20% silica sol. Thissolution was mixed with a solution obtained by dissolving, in 216 g of3.3% nitric acid, 243.7 g of nickel nitrate, 29.16 g of chromiumnitrate, 7.79 g of zirconium oxynitrate, 10.32 g of potassium nitrate,40 g of citric acid, 35.33 g of iron nitrate and 21.21 g of bismuthnitrate, and thus a slurry was obtained. To this slurry was added asolution obtained by adding to 208 g of water, 4.65 g of metallictellurium, 3.9 g of ammonium paramolybdate and 16 g of aqueous hydrogenperoxide, followed by stirring at 95-100° C. to dissolve the components.To this slurry with stirring was added 15% aqueous ammonia to adjust thepH to 7.7, and this slurry was mixed with 138.3 g of an iron antimonatepowder to obtain a mixture.

Said mixture was spray dried by a rotary disk type spray dryer with aninlet temperature of 330° C. and an outlet temperature of 160° C. Theparticles were heat treated at 250° C. for 2 hours and at 400° C. for 2hours, and finally calcined in a fluidization kiln at 590° C. for 3hours.

EXAMPLE 1-2

A catalyst having the same composition as of Example 1-1 was prepared bythe following method.

154.4 g of ammonium paramolybdate was dissolved in 1730 g of pure water,and, then, 3.3 g of 85% phosphoric acid was added to the solution. Thesolution was mixed with 1750 g of 20% silica sol. This solution wasmixed with a solution obtained by dissolving, in 216 g of 3.3% nitricacid, 243.7 g of nickel nitrate, 29.16 g of chromium nitrate, 7.79 g ofzirconium oxynitrate, 10.32 g of potassium nitrate, 20 g of citric acidand 21.21 g of bismuth nitrate, and thus a slurry was obtained. To thisslurry with stirring was added 15% aqueous ammonia to adjust the pH to7.7, and then the slurry was heat treated at 100° C. for 1.5 hour underrefluxing.

To 208 g of water were added 4.65 g of metallic tellurium, 3.9 g ofammonium paramolybdate and 16 g of aqueous hydrogen peroxide, followedby stirring at 95-100° C. to dissolve the components. This solution wascooled to room temperature, and 20 g of citric acid and 35.33 g of ironnitrate were dissolved therein. 15% aqueous ammonia was added to theresulting solution with stirring to adjust the pH to 9.2, and, further,99.1 g of ammonium paramolybdate was added thereto little by little anddissolved. Then, aqueous ammonia was added to adjust the pH to 7. Thissolution was mixed with the above heat treated slurry and mixed with138.3 g of an iron antimonate powder.

The resulting mixture was spray dried and heat treated in the samemanner as in Example 1-1, and finally calcined in a fluidization kiln at580° C. for 3 hours.

EXAMPLE 2-1

A catalyst having the composition ofMo₁₀Bi_(0.3)Fe_(4.5)Sb₇Ni_(5.75)Cr_(0.7)La_(0.2)V_(0.05)K_(0.7)P_(0.2)Te_(0.25)O_(59.8)(SiO₂)₄₀(atomic ratio) was prepared by the following method.

237.2 g of ammonium paramolybdate was dissolved in 1730 g of pure water,and, then, 3.10 g of 85% phosphoric acid was added to the solution. Thesolution was mixed with 1615 g of 20% silica sol. This solution wasmixed with a solution obtained by dissolving, in 210 g of 3.3% nitricacid, 224.6 g of nickel nitrate, 37.6 g of chromium nitrate, 11.63 g oflanthanum nitrate, 9.51 g of potassium nitrate, 40 g of citric acid,32.56 g of iron nitrate and 19.55 g of bismuth nitrate, and thus aslurry was obtained. To this slurry with stirring was added 15% aqueousammonia to adjust the pH to 7.7, and then the slurry was heat treated at100° C. for 1.5 hour under refluxing.

7.71 g of telluric acid was dissolved in 200 g of pure water. Thissolution was mixed with the above heat treated slurry and mixed with186.4 g of an iron antimonate powder.

The resulting mixture was spray dried and heat treated in the samemanner as in Example 1-1, and finally calcined in a fluidization kiln at590° C. for 3 hours.

EXAMPLE 2-2

A catalyst having the same composition as of Example 2-1 was prepared bythe following method.

237.2 g of ammonium paramolybdate was dissolved in 1730 g of pure water,and then 3.10 g of 85% phosphoric acid was added to the solution. Theresulting solution was mixed with 1615 g of 20% silica sol. Thissolution was mixed with a solution obtained by dissolving, in 216 g of3.3% nitric acid, 224.6 g of nickel nitrate, 37.6 g of chromium nitrate,11.63 g of lanthanum nitrate, 9.51 g of potassium nitrate, 20 g ofcitric acid and 19.55 g of bismuth nitrate, and thus a slurry wasobtained. To this slurry with stirring was added 15% aqueous ammonia toadjust the pH to 7.7, and then the slurry was heat treated at 100° C.for 1.5 hour under refluxing.

7.71 g of telluric acid, 20 g of citric acid and 32.56 g of iron nitratewere dissolved in 200 g of water. This solution was mixed with the aboveheat treated slurry and mixed with 186.4 g of an iron antimonate powder.

The resulting mixture was spray dried and heat treated in the samemanner as in Example 1-1, and finally calcined in a fluidization kiln at590° C. for 3 hours.

EXAMPLE 3

A catalyst having the composition ofMo₁₀Bi_(0.4)Fe_(4.5)Sb₁₀Ni_(5.75)Cr_(1.0)Ce_(0.2)Ta_(0.05)K_(0.5)P_(0.2)Cs_(0.1)O_(65.8)(SiO₂)₄₀(atomic ratio) was prepared by the following method.

219.2 g of ammonium paramolybdate was dissolved in 1730 g of pure water,and then 2.86 g of 85% phosphoric acid was added thereto. The resultingsolution was mixed with 1490 g of 20% silica sol. This solution wasmixed with a solution obtained by dissolving, in 210 g of 3.3% nitricacid, 207.6 g of nickel nitrate, 49.67 g of chromium nitrate, 10.78 g ofcerium nitrate, 8.79 g of potassium nitrate, 2.42 g of cesium nitrate,1.32 g of tantalum oxide, 20 g of citric acid and 21.21 g of bismuthnitrate, and thus a slurry was obtained. To this slurry with stirringwas added 15% aqueous ammonia to adjust the pH to 7.7, and then theslurry was heat treated at 100° C. for 1.5 hour under refluxing.

20 g of citric acid and 35.33 g of iron nitrate were dissolved in 100 gof water. To this solution with stirring was added 15% aqueous ammoniato adjust the pH to 8. This solution was mixed with the above heattreated slurry and then mixed with 138.3 g of an iron antimonate powder.

The resulting mixture was spray dried and heat treated in the samemanner as in Example 1-1, and finally calcined in a fluidization kiln at600° C. for 3 hours.

EXAMPLE 4-1

A catalyst having the composition ofMo₁₀Bi_(0.4)Fe_(0.6)Ni_(5.75)Cr_(0.5)Zr_(0.2)K_(0.7)P_(0.2)Te_(0.25)O_(39.8)(SiO₂)₄₀(atomic ratio) was prepared by the following method.

309.5 g of ammonium paramolybdate was dissolved in 1800 g of pure water,and then 4.04 g of 85% phosphoric acid was added thereto. This solutionwas mixed with a solution obtained by dissolving, in 250 g of 3.3%nitric acid, 293.2 g of nickel nitrate, 35.08 g of chromium nitrate,9.37 g of zirconium oxynitrate, 12.41 g of potassium nitrate and 34.02 gof bismuth nitrate, followed by mixing with 2107 g of 20% silica sol,and thus a slurry was obtained. To this slurry with stirring was added15% aqueous ammonia to adjust the pH to 8. To this slurry was added asolution obtained by dissolving 10.1 g of telluric acid and 35.33 g ofiron nitrate in 200 g of pure water, followed by mixing them.

The resulting mixture was spray dried and heat treated in the samemanner as in Example 1-1, and finally calcined in a fluidization kiln at580° C. for 3 hours.

EXAMPLE 4-2

A catalyst having the same composition as of Example 4-1 was prepared bythe following method.

185.7 g of ammonium paramolybdate was dissolved in 1730 g of pure water,and then 4.04 g of 85% phosphoric acid was added thereto. This solutionwas mixed with a solution obtained by dissolving, in 216 g of 3.3%nitric acid, 293.2 g of nickel nitrate, 35.08 g of chromium nitrate,9.37 g of zirconium oxynitrate, 12.41 g of potassium nitrate, 24 g ofcitric acid and 34.02 g of bismuth nitrate, followed by mixing with 2107g of 20% silica sol, and, as a result, a slurry was obtained. To thisslurry with stirring was added 15% aqueous ammonia to adjust the pH to7.7, and then the slurry was heat treated at 100° C. for 1.5 hour underrefluxing.

To 208 g of pure water were added 5.59 g of a metallic tellurium powder,4.6 g of ammonium paramolybdate, 19 g of 31% aqueous hydrogen peroxideand 19 g of water, followed by stirring and dissolving at 95-100° C. Thesolution was cooled to room temperature, and 20 g of citric acid and35.33 g of iron nitrate were dissolved therein. To the solution withstirring was added 15% aqueous ammonia to adjust the pH to 9.2, then119.2 g of ammonium paramolybdate was added thereto little by little,and furthermore 15% aqueous ammonia was added to adjust the pH to 7.This solution was added to the above heat treated slurry and these weremixed.

The resulting mixture was spray dried and heat treated in the samemanner as in Example 1-3, and finally calcined in a fluidization kiln at580° C. for 3 hours.

EXAMPLE 5

A catalyst having the composition ofMo₁₀Bi_(0.4)Fe_(0.6)Ni_(5.75)Cr_(1.5)La_(0.2)Mn_(0.2)K_(0.7)P_(0.2)Te_(0.25)O_(41.6)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example4-2.

EXAMPLE 6

A catalyst having the composition ofMo₁₀Bi_(0.8)Fe_(4.5)Sb₄Ni_(6.5)Cr_(0.6)Zr_(0.1)La_(0.1)K_(0.7)P_(0.5)B_(0.3)O_(55.8)(SiO₂)₅₀(atomic ratio) was prepared in accordance with the method of Example1-2, except that the iron antimonate containing phosphorus and boron (atan atomic ratio of 0.075 to Sb, respectively) was used.

EXAMPLE 7

A catalyst having the composition ofMo₁₀Bi₁Fe_(4.5)Sb₄Ni₆Cr_(0.5)Zr_(0.1)Zn_(0.2)Nb_(0.05)K_(0.6)P_(0.5)B_(0.3)Te_(0.25)O_(56.0)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example 6.

EXAMPLE 8

A catalyst having the composition ofMo₁₀Bi₁Fe_(4.5)Sb₄Ni_(5.5)Cr_(0.5)La_(0.1)Mg_(0.5)K_(0.6)P_(0.2)Te_(0.25)O_(54.5)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example1-2.

EXAMPLE 9

A catalyst having the composition ofMo₁₀Bi_(1.5)Fe_(4.5)Sb₄Ni₅Cr_(0.3)La_(0.07)Co₁K_(0.6)P_(0.2)Te_(0.25)O_(55.3)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example1-2.

EXAMPLE 10

A catalyst having the composition ofMo₁₀Bi_(0.4)Fe_(4.5)Sb₄Ni₇Cr_(0.4)La_(0.1)W_(0.1)K_(0.5)P_(0.5)B_(0.3)Rb_(0.1)O_(55.4)(SiO₂)₄₀ (atomic ratio) was prepared in accordance with the method ofExample 6.

EXAMPLE 11

A catalyst having the composition ofMo₁₀Bi_(0.3)Fe_(7.6)Sb_(7.7)Ni₆Cr_(0.5)Zr_(0.1)La_(0.1)K_(0.6)P_(0.2)O_(65.5)(SiO₂)₆₀(atomic ratio) was prepared in accordance with the method of Example1-2.

COMPARATIVE EXAMPLE 1

A catalyst having the composition ofMo₁₀Bi_(0.3)Fe_(4.4)Sb_(4.2)Ni_(5.75)Zr_(0.2)K_(0.7)P_(0.2)Te_(0.25)O_(53.0)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example1-2, except that the zirconium component was not added.

COMPARATIVE EXAMPLE 2

A catalyst having the composition ofMo₁₀Bi_(0.3)Fe_(4.4)Sb_(4.2)Ni_(5.75)Ce_(0.2)K_(0.7)P_(0.2)Te_(0.25)O_(55.4)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example1-2, except that the chromium component was not added.

COMPARATIVE EXAMPLE 3

A catalyst having the composition ofMo₁₀Bi_(0.3)Fe_(4.4)Sb_(4.2)Ni_(5.75)Ce_(0.2)K_(0.7)P_(0.2)Te_(0.25)O_(55.4)(SiO₂)₄₀(atomic ratio) was prepared in accordance with the method of Example1-2.

The catalysts of the above examples and comparative examples weresubjected to the catalyst activity test as mentioned above. The resultsare shown in Table 1.

INDUSTRIAL APPLICABILITY

The catalysts of the present invention can give a high yield ofunsaturated nitrites by ammoxidation of olefins, especiallyacrylonitrile by ammoxidation of propylene, and besides they can inhibitcombustion of ammonia.

TABLE 1 Catalyst composition (atomic ratio) Mo Bi Fe Sb Ni Cr F G H K XY SiO₂ Example 1-1 10 0.3 4.4 4.2 5.75 0.5 Zr 0.2 — — 0.7 P 0.2 Te 0.25— 40 1-2 10 0.3 4.4 4.2 5.75 0.5 Zr 0.2 — — 0.7 P 0.2 Te 0.25 — 40 2-110 0.3 4.5 7.0 5.75 0.7 La 0.2 — V 0.05 0.7 P 0.2 Te 0.25 — 40 2-2 100.3 4.5 7.0 5.75 0.7 La 0.2 — V 0.05 0.7 P 0.2 Te 0.25 — 40 3 10 0.4 4.510.0  5.75 1.0 Ce 0.2 — Ta 0.05 0.5 P 0.2 Cs 0.1 40 4-1 10 0.4 0.6 —5.75 0.5 Zr 0.2 — — 0.7 P 0.2 Te 0.25 — 40 4-2 10 0.4 0.6 — 5.75 0.5 Zr0.2 — — 0.7 P 0.2 Te 0.25 — 40 5 10 0.4 0.6 — 5.75 1.5 La 0.2 Mn 0.2 —0.7 P 0.2 Te 0.25 — 40 6 10 0.8 4.5 4.0 6.50 0.6 Zr 0.1 La 0.1 — — 0.7 P0.5 B 0.3 — 40 7 10 1.0 4.5 4.0 6.00 0.5 Zr 0.1 Zn 0.2 Nb 0.05 0.6 P 0.5Te 0.25 — 50 B 0.3 8 10 1.0 4.5 4.0 5.50 0.5 La 0.1 Mg 0.5 — 0.6 P 0.2Te 0.25 — 40 9 10 1.5 4.5 4.0 5.00 0.3 La 0.07 Co 1.0 — 0.6 P 0.2 Te0.25 — 40 10 10 0.4 4.5 4.0 7.00 0.4 La 0.1 — W 0.1 0.5 P 0.5 B 0.3 Rb0.1 40 11 10 0.3 7.6 7.7 6.00 0.5 Zr 0.1 La 0.1 — — 0.6 P 0.2 — 60Compara- tive Example 1 10 0.3 4.4 4.2 5.75 0.5 — — — 0.7 P 0.2 Te 0.25— 40 2 10 0.3 4.4 4.2 5.75 — Zr 0.2 — — 0.7 P 0.2 Te 0.25 — 40 3 10 0.34.4 4.2 5.75 — Ce 0.2 — — 0.7 P 0.2 Te 0.25 — 40 Reaction ConditionsCalcining Reaction Contact Temperature Temperature Time Yield ofConversion Selectivity Combustion Rate ° C. ° C. sec AN¹⁾ % of C3²⁾ %AN³⁾ % of NH₃ % Example 1-1 590 440 2.25 84.5 98.5 85.9 11 1-2 590 4402.25 85.7 98.5 87.0 10 2-1 590 435 2.50 84.5 98.5 85.7 9 2-2 590 4352.50 84.7 98.6 85.9 8 3 600 440 2.50 85.1 98.5 86.4 7 4-1 580 440 2.5084.2 98.2 85.7 15 4-2 580 440 2.25 84.8 98.6 86.0 13 5 580 435 2.50 84.198.9 85.0 10 6 560 440 2.50 84.2 98.1 85.8 12 7 560 440 2.50 83.9 98.085.6 11 8 555 440 2.25 84.1 98.8 85.1 10 9 535 440 2.25 83.9 98.5 85.216 10 600 440 3.00 85.5 98.3 87.0 6 11 590 440 2.50 85.6 98.7 86.7 9Compara- tive Example 1 590 440 1.50 82.1 98.3 83.5 5 2 550 440 1.7583.1 98.5 84.4 18 3 570 440 2.50 83.6 98.6 84.8 25 Note) ¹⁾AN:Acrylonitrile ²⁾C3: Propylene

What is claimed is:
 1. A catalyst composition represented by thefollowing empirical formula which is useful in production of unsaturatednitrites by ammoxidation:Mo₁₀Bi_(a)Fe_(b)Sb_(c)Ni_(d)Cr_(e)F_(f)G_(g)H_(h)K_(k)X_(x)Y_(y)O_(i)(SiO₂)_(j)wherein Mo, Bi, Fe, Sb, Ni, Cr and K represent molybdenum, bismuth,iron, antimony, nickel, chromium and potassium, respectively, Frepresents at least one element selected from the group consisting ofzirconium, lanthanum and cerium, G represents at least one elementselected from the group consisting of magnesium, cobalt, manganese andzinc, H represents at least one element selected from the groupconsisting of vanadium, niobium, tantalum and tungsten, X represents atleast one element selected from the group consisting of phosphorous,boron and tellurium, Y represents at least one element selected from thegroup consisting of lithium, sodium, rubidium and cesium, O representsoxygen and SiO₂ represents silica, the suffixes a, b, c, d, e, f, g, h,i, j, k, x and y represent a ratio of atoms or atomic groups, a=0.1-3,b=0.3-15, c=0-20, d=3-8, e=0.2-2, f=0.05-1, e/f>1, g=0-5, h=0-3, k=0.1,x=0-3, y=0-1, i is the number of oxygen produced by bonding of the aboverespective components, and j=0-100.
 2. A catalyst composition accordingto claim 1 which contains iron antimonate.
 3. A catalyst compositionaccording to claim 1 or 2, wherein said metal oxide catalyst is afluidized bed catalyst prepared by spray drying an aqueous slurry havinga pH of 6 or higher and containing at least starting materials formolybdenum, bismuth and iron components and a chelating agent andcalcining the resulting product.
 4. A method for producing the catalystcomposition of claim 1 or 2 which comprises mixing an aqueous slurryhaving a pH of 6 or higher and containing at least a part of a startingmaterial for molybdenum and a starting material for at least one elementselected from the group consisting of nickel, cobalt, magnesium,chromium, manganese and zinc with a solution or slurry containing astarting material for tellurium or a starting material for iron, anddrying and calcining the mixture.
 5. A method for producing the catalystcomposition of claim 1 or 2 which comprises heat treating an aqueousslurry having a pH of 6 or higher and containing at least a part of astarting material for molybdenum and a starting material for at leastone element selected from the group consisting of nickel, cobalt,magnesium, chromium, manganese and zinc at a temperature of 50-120° C.for at least 10 minutes, mixing a starting material for tellurium or astarting material for iron with said heat treated slurry, and thendrying and calcining the mixture.
 6. A method for producing the catalystcomposition of claim 1 or 2 which comprises mixing an aqueous slurryhaving a pH of 6 or higher and containing at least a part of a startingmaterial for molybdenum and a starting material for at least one elementselected from the group consisting of nickel, cobalt, magnesium,chromium, manganese and zinc with a solution or slurry containing astarting material for tellurium and a starting material for iron, anddrying and calcining the mixture.
 7. A method for producing the catalystcomposition of claim 1 or 2 which comprises heat treating an aqueousslurry having a pH of 6 or higher and containing at least a part of astarting material for molybdenum and a starting material for at leastone element selected from the group consisting of nickel, cobalt,magnesium, chromium, manganese and zinc at a temperature of 50-120° C.for at least 10 minutes, mixing a starting material for tellurium and astarting material for iron with said heat treated slurry, and thendrying and calcining the mixture.
 8. A catalyst composition according toclaim 1, wherein j=20-80.
 9. A process for producing an unsaturatednitrile comprising ammoxidating an olefin in the presence of a catalystcomposition according to claim
 1. 10. A process for producing anunsaturated nitrile comprising ammoxidating an olefin in the presence ofa catalyst composition according to claim 2.